It has been known that, for example, a lens for optical communication is surface-mounted on a substrate (for example, a silicon bench) including a laser diode and an end portion of an optical fiber mounted thereon, and focuses light output from the laser diode on the optical fiber.
A glass lens is used for this type of lens instead of using a typical resin lens (refer to Patent Literature 1).
A square lens having a circumferential shape of the glass lens squared, is used in Patent Literature 1. A plane (a reference face) is preferably provided at the circumference of the lens for surface-mounting the lens on a substrate (for example, a silicon bench). That is, the plane at the circumference of the lens is disposed so as to abut on a mounting face of the substrate (a plane on the substrate) on which the lens is mounted. Thus, the lens can be stably disposed on the mounting face of the substrate. In addition, in a case where arrangement relationship between an optical axis of the lens and the plane has been determined and the plane is the reference face, only abutting the reference face against the mounting face, determines, for example, a distance of the optical axis from the substrate. Therefore, the square lens can easily adhere to and fix to the mounting face of the substrate, using for example, an ultraviolet curable resin.
Providing a reference face to an aspheric lens that has been previously molded, by post-processing, such as dicing and polishing, is also performed except the above square lens.
In a case where a ball lens formed by polishing is used, it has been known a method of sealing the ball lens in a body tube provided by cutting a stainless steel material or a can formed by pressing a nickel alloy, with low-melting-point glass. In this case, the ball lens is mounted on the substrate through the body tube or the can.